Yet another thing that I had an idea about and had to stay up till one in the morning to finish because otherwise I'd forget or it'd bug me if I only started but didn't finish it.
Warning: Little bit of violence, but it's kind of normal in our fandom.
Dean isn't sure how he realizes it before Sam does, but he knows on instinct that the person standing before them is not Castiel, though he may be wearing the same face. There's something off about him from the get go, but the difference is so miniscule that not even his nerdy brother can deduce the problem right away. Dean knows in the way that 'Cas', who he now knows to be the shapeshifter they'd been hunting in a small town in Iowa, never looks him in the eye. It would seem like normal behavior to anyone else, yet Dean is so used to his intense staring competitions with the ex-angel that the lack of it is completely out of the ordinary. He sees it in the way that the shifter actually gives him personal space rather than encroaching upon it like a creeper.
He doesn't even have to rely on any tests to know that this isn't Cas and it seems that only he realizes this. Which is probably why Sam lets out a shocked cry when Dean tackles 'Cas' to the ground, slicing through skin with a silver knife.
"Dean, what the hell?!" Sam shouts as he watches the other two fight, thankful that their motel is deserted for the most part.
"Where's Cas, you son of a bitch?" Dean yells into the shifter's face, completely ignoring Sam's question.
"I am Cas. Why are you attacking me?" not Cas replies innocently.
"Don't play games with me! Tell me before I rip you to pieces with this," Dean says, pressing the knife into the shifter's arm.
The area where Dean cuts sizzles and the shifter hisses in pain, unsuccessfully trying to throw Dean off of him. The hunter tries not to falter as he presses the blade in deeper, because even though he knows that this isn't his friend, it's still Cas's face contorting in pain as he tries to get away from his knife.
"Dean, please, it's me. Stop it!" the shifter cries.
All it takes is that one second of hesitation before the next cut and the shifter punches him square in the jaw before pushing him off and into the wall. Even if that was really Cas on the ground, being attacked by Dean, Sam knows that he wouldn't fight back and especially not like that. It is this knowledge that spurs him into action, going for the knife that fell out of Dean's hand when he was thrown into the wall.
His size works to his advantage, long arm reaching just enough to cut into fake Cas' arm, making him recoil and giving Dean time to recover. The older hunter pushes off from the wall, using his momentum in a punch that renders the shifter unconscious.
"Help me with this," Dean growls, hefting the shifter up and making Sam keep watch while he takes the dead weight to their car.
Luck seems to be in their favor and the shifter doesn't wake up until Sam and Dean have successfully reached the middle of nowhere to 'persuade' him into telling them where Cas is. Sam watches his brother with concern in his eyes. There's something dark in Dean's eyes that he hasn't seen in a while and he almost feels bad for this monster who had the gall to mess with his brother's angel.
The sound of Dean's hand slapping against skin echoes in the empty walls of the old run down factory they reside in and the shifter grunts and grumbles into wakefulness. He glares up at the two brothers, clearly intent on being uncooperative. Sam wants to tell him not to underestimate a pissed off Winchester, especially when said Winchester is his older brother, who is very well versed in torture methods, courtesy of Alastair.
"So, how'd you know?" he finally asks and Sam doesn't say that he wants to know the answer to that question too.
"It was pretty obvious," Dean replies.
"I thought I was being pretty subtle," the shifter says mournfully, like he's ashamed for being found out.
"Of course you did," Dean laughs. "See, that's the thing about Cas. He's a bit of an odd one. No concept of personal space. Always staring at me like some creeper trying to see into my soul, which is probably what he's doing. You didn't do that,"
"Wait," the shifter says disbelievingly, "I was too normal?"
"Yeah. Now I'm going to ask you again. Where. Is. He?" Dean says, punctuating each word of his last sentence with a jab of his knife and promises of more pain if the shifter doesn't answer.
"Probably bleeding out in a sewer somewhere," the shifter sneers. "Don't even remember where I left him,"
"Wrong answer,"
Dean plunges the silver blade into the shifter's stomach, causing the creature to cry out in pain, writhing against its restraints. Sam watches as Dean twists the knife, growls out his question one more time in a low voice, though it's not like anyone can hear them.
"Where's Cas?" he demands.
"I told you I don't remember. And even if I did, I wouldn't tell you,"
Fake Cas screams again as Dean removes the knife, rather painfully, before embedding it into the shifter's shoulder. The game of question and answer goes on for a long while, each incorrect answer punctuated with a scream from someone wearing their friend's body. Sam tries to intervene once, because he can see the toll it's taking on Dean to keep doing this to someone, something, that looks exactly like his best friend/angel/whatever Cas is to Dean. All he gets in response is a glare that, if he were a normal person, would have him running for his life.
Finally, after what seems like an eternity of screaming, the shifter gasps out, "Stop!"
Dean holds his blade above the shifter's chest, looking down expectantly.
"The old subway station that was never built. That's where I left him," he grits out, voice raspy.
"Thanks a lot," Dean replies with a sarcastic smile and plunges the knife into its chest.
After burning the body, because having some random homeless person wandering in to squat and finding a dead body is not preferable, they pack into the Impala and head to where the shifter told them Cas was. Dean drives nearly fifteen miles over the speed limit and only slows down when Sam tells him that getting pulled over by the cops would only delay them more. But he doesn't loosen his white-knuckled grip on the steering wheel.
"Dean," Sam starts.
"What?" Dean grumbles, not bothering to cast his eyes in his brother's direction.
"Are you okay?" he asks.
This time, Dean rolls his eyes before taking his eyes off the road and looking at Sam, simutaneously annoyed and confused.
"Why wouldn't I be? We did just get rid of the shifter we came here to hunt," he says.
"Yeah, that ended up having Cas's face and voice, and well, everything. I was there, remember? It was hard for you, I could tell," Sam says.
Dean scoffs at that and returns his eyes to the road.
"I don't know what you mean," he says quietly.
"Yes you do. You just don't want to admit that-,"
"Shut up Sam. Whatever you're thinking or trying to say, just stop it,"
He can be stubborn as a mule when he wants to be. Sam drops it.
It takes them another five minutes to get the old station that Cas should be in. Each one ticks by like an hour. The smell of shedded, rotting skin doesn't phase him as much as it does Sam, but it still reeks to high Heaven, or wherever, down here. He doesn't focus on the odor though as he scans his flashlight around almost frantically, cries of Cas's name echoing off the walls.
He strains his ears to hear anything else but his own voice echoing back at him, listening for that gravelly voice that he knows so well. After another shout of his angel's name, he hears a reply, albeit a weak one. He rounds the corner and finds Cas there, curled up in a corner, blood on his shirt from what looks like a cut in his shoulder. A protective sort of anger flares up in him and makes him wish he hadn't killed that shifter so he could take everything out on it later. But he ignores that for now, shoves it down along with all the other confusing feelings he has about Cas and rushes to his side.
"Cas! Thank God you're okay," he breathes, assessing him for any more damage, cursing under his breath when he finds brusies mottling Cas's skin. At least the wound in his shoulder is no longer bleeding, but Cas's white shirt is probably unsalvageable. He doesn't really care about Cas's clothes though and hauls the fallen angel to his feet, letting him drape an arm over his shoulder for support.
"Dean, the shifter, he-,"
"He's dead,"
"You killed him?"
"Obviously," Dean says. "Dammit Cas, why didn't you call to tell me you were okay? Or at least try to get out of here?"
"My phone would not work down here. And I could not find my way out. I'm sorry,"
"Well, as along as you're alright, it's fine,"
Needless to say, after they wind their way back up to the surface, Dean never takes his eyes off Castiel. He even lets Sam drive his precious baby for once, preferring to stay in the backseat with Cas and fuss over his wounds like a mother hen. It would almost be funny if not for the hint of almost hysteria in Dean's eyes over almost losing Cas again.
"Dean, I told you, I'm fine. I will heal, although the process may take longer now that I am human. You needn't worry yourself,"
"Shut it, Cas," Dean grumbles, with no real malice behind the words. He takes one of Cas's hands in his own, examining it and finding brusies along the knuckles. He smiles and looks up at the other man.
"I fought back," Cas explains.
"I can see that," he replies.
He glances at Sam, who's eyes are focused on the road like a responsible driver and back to Cas, bringing up his hand and kissing the brusies there. Cas looks like he wants to say something but the words die on his lips.
"Don't ever do that again," Dean instructs, voice barely above a whipser.
"Do what?"
There are so many things he wants to say to that. Don't die on me. Don't leave me alone. But instead he settles for "Don't go disappearing on me, man," which is close enough in his book. The unspoken 'I need you' passes between them with their stare that he's so used to.
"Okay," Cas replies.
They stop at their motel to gather their things before heading back to the bunker. Dean sits in the back with Cas again and laces their fingers together, glaring at Sam in the rearview mirror and daring him to say anything. It may have taken him a long time to admit it or even acknowledge it, but Cas is everything to him. Other than Sam, he's the only thing that Dean has left. He can't lose him again. Once was bad enough when he'd walked into that apartment and seen the reaper stab his once angel with the blade. He was certainly angry enough, having practically seen red at the time, but the only thing that had been coursing through his veins at the time was thoughts of please don't be dead. And it had felt like his world came crashing down around him when his beloved friend showed no signs of life. Despite being an utter and complete universe-ruining douchebag, bringing Cas back to him is one thing that he's actually grateful to Gadreel for.
Halfway there, Cas falls asleep against him and he can't help but chuckling softly at the snores coming from him. He lets go of Cas's hand in favor of dragging him closer and ends up combing his fingers through his hair, smiling when Cas grumbles in his sleep and snuggles closer. Sam lets out an amused huff from the driver's seat and Dean kicks the back of it like he's a five year old, but ultimately doesn't care what his little brother thinks. The only real thing that matters to him now is that he's got his angel back, - and halo or no halo, Cas is always going to be his angel - and he's not going to let him go any time soon.